The Labile Iron Pool Reacts Rapidly and Catalytically with Peroxynitrite

While investigating peroxynitrite-dependent oxidation in murine RAW 264.7 macrophage cells, we observed that removal of the Labile Iron Pool (LIP) by chelation increases the intracellular oxidation of the fluorescent indicator H2DCF, so we concluded that the LIP reacts with peroxynitrite and decreases the yield of peroxynitrite-derived oxidants. This was a paradigm-shifting finding in LIP biochemistry and raised many questions. In this follow-up study, we address fundamental properties of the interaction between the LIP and peroxynitrite by using the same cellular model and fluorescence methodology. We have identified that the reaction between the LIP and peroxynitrite has catalytic characteristics, and we have estimated that the rate constant of the reaction is in the range of 106 to 107 M−1s−1. Together, these observations suggest that the LIP represents a constitutive peroxynitrite reductase system in RAW 264.7 cells.

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Faculty Opinions recommendation of Mitochondrial Hsp60, resistance to oxidative stress, and the labile iron pool are closely connected in Saccharomyces cerevisiae.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1009153.119858 ◽

2002 ◽

Author(s):

Thomas Nystrom

Keyword(s):

Oxidative Stress ◽

Saccharomyces Cerevisiae ◽

Labile Iron Pool ◽

Labile Iron ◽

Iron Pool

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Analysis of yggX and gshA Mutants Provides Insights into the Labile Iron Pool in Salmonella enterica

Journal of Bacteriology ◽

10.1128/jb.00639-08 ◽

2008 ◽

Vol 190 (23) ◽

pp. 7608-7613 ◽

Cited By ~ 11

Author(s):

Michael P. Thorgersen ◽

Diana M. Downs

Keyword(s):

Salmonella Enterica ◽

Iron Chelator ◽

Fenton Chemistry ◽

Labile Iron Pool ◽

Growth Defects ◽

Labile Iron ◽

Iron Pool ◽

Mutant Phenotypes ◽

Permeable Iron ◽

Iron Chelator Deferoxamine

ABSTRACT Strains of Salmonella enterica lacking YggX and the cellular reductant glutathione exhibit defects similar to those resulting from iron deficiency and oxidative stress. Mutant strains are sensitive to hydrogen peroxide and superoxide, deregulate the expression of the Fur-regulated gene entB, and fail to grow on succinate medium. Suppression of some yggX gshA mutant phenotypes by the cell-permeable iron chelator deferoxamine allowed the conclusion that increased levels of cellular Fenton chemistry played a role in the growth defects. The data presented are consistent with a scenario in which glutathione acts as a physiological chelator of the labile iron pool and in which YggX acts upstream of the labile iron pool by preventing superoxide toxicity.

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Phosphoinositide-3-kinase inhibition elevates ferritin level resulting depletion of labile iron pool and blocking of glioma cell proliferation

Biochimica et Biophysica Acta (BBA) - General Subjects ◽

10.1016/j.bbagen.2018.12.013 ◽

2019 ◽

Vol 1863 (3) ◽

pp. 547-564 ◽

Cited By ~ 2

Author(s):

Poonam Gupta ◽

Pratibha Singh ◽

Hriday S. Pandey ◽

Pankaj Seth ◽

Chinmay K. Mukhopadhyay

Keyword(s):

Cell Proliferation ◽

Glioma Cell ◽

Ferritin Level ◽

Kinase Inhibition ◽

Labile Iron Pool ◽

Glioma Cell Proliferation ◽

Labile Iron ◽

Phosphoinositide 3 Kinase ◽

Iron Pool

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Labile iron pool correlates with iron content in the nucleus and the formation of oxidative DNA damage in mouse lymphoma L5178Y cell lines.

Acta Biochimica Polonica ◽

10.18388/abp.2003_3729 ◽

2003 ◽

Vol 50 (1) ◽

pp. 211-215 ◽

Cited By ~ 15

Author(s):

Marcin Kruszewski ◽

Teresa Iwaneńko

Keyword(s):

Hydrogen Peroxide ◽

Dna Damage ◽

Cell Lines ◽

Oxidative Dna Damage ◽

Transition Metal Ions ◽

Dna Lesions ◽

Labile Iron Pool ◽

Labile Iron ◽

Iron Pool ◽

Mouse Lymphoma

Labile iron pool (LIP) constitutes a crossroad of metabolic pathways of iron-containing compounds and is midway between the cellular need for iron, its uptake and storage. In this study we investigated oxidative DNA damage in relation to the labile iron pool in a pair of mouse lymphoma L5178Y (LY) sublines (LY-R and LY-S) differing in sensitivity to hydrogen peroxide. The LY-R cells, which are hydrogen peroxide-sensitive, contain 3 times more labile iron than the hydrogen peroxide-resistant LY-S cells. Using the comet assay, we compared total DNA breakage in the studied cell lines treated with hydrogen peroxide (25 microM for 30 min at 4 degrees C). More DNA damage was found in LY-R cells than in LY-S cells. We also compared the levels of DNA lesions sensitive to specific DNA repair enzymes in both cell lines treated with H(2)O(2). The levels of endonuclease III-sensitive sites and Fapy-DNA glycosylase-sensitive sites were found to be higher in LY-R cells than in LY-S cells. Our data suggest that the sensitivity of LY-R cells to H(2)O(2) is partially caused by the higher yield of oxidative DNA damage, as compared to that in LY-S cells. The critical factor appears to be the availability of transition metal ions that take part in the OH radical-generating Fenton reaction (very likely in the form of LIP).

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The Cellular Labile Iron Pool and Intracellular Ferritin in K562 Cells

Blood ◽

10.1182/blood.v94.6.2128 ◽

1999 ◽

Vol 94 (6) ◽

pp. 2128-2134 ◽

Cited By ~ 109

Author(s):

Abraham M. Konijn ◽

Hava Glickstein ◽

Boris Vaisman ◽

Esther G. Meyron-Holtz ◽

Itzchak N. Slotki ◽

...

Keyword(s):

Biological Effects ◽

Ferritin Level ◽

Regulatory Protein ◽

Iron Chelation ◽

K562 Cells ◽

Iron Chelator ◽

Labile Iron Pool ◽

Cellular Iron ◽

Labile Iron ◽

Iron Pool

Abstract The labile iron pool (LIP) harbors the metabolically active and regulatory forms of cellular iron. We assessed the role of intracellular ferritin in the maintenance of intracellular LIP levels. Treating K562 cells with the permeant chelator isonicotinoyl salicylaldehyde hydrazone reduced the LIP from 0.8 to 0.2 μmol/L, as monitored by the metalo-sensing probe calcein. When cells were reincubated in serum-free and chelator-free medium, the LIP partially recovered in a complex pattern. The first component of the LIP to reappear was relatively small and occurred within 1 hour, whereas the second was larger and relatively slow to occur, paralleling the decline in intracellular ferritin level (t½= 8 hours). Protease inhibitors such as leupeptin suppressed both the changes in ferritin levels and cellular LIP recovery after chelation. The changes in the LIP were also inversely reflected in the activity of iron regulatory protein (IRP). The 2 ferritin subunits, H and L, behaved qualitatively similarly in response to long-term treatments with the iron chelator deferoxamine, although L-ferritin declined more rapidly, resulting in a 4-fold higher H/L-ferritin ratio. The decline in L-ferritin, but not H-ferritin, was partially attenuated by the lysosomotrophic agent, chloroquine; on the other hand, antiproteases inhibited the degradation of both subunits to the same extent. These findings indicate that, after acute LIP depletion with fast-acting chelators, iron can be mobilized into the LIP from intracellular sources. The underlying mechanisms can be kinetically analyzed into components associated with fast release from accessible cellular sources and slow release from cytosolic ferritin via proteolysis. Because these iron forms are known to be redox-active, our studies are important for understanding the biological effects of cellular iron chelation.

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Detection of iron-containing proteins contributing to the cellular labile iron pool by a native electrophoresis metal blotting technique

Journal of Inorganic Biochemistry ◽

10.1016/s0162-0134(01)00232-x ◽

2001 ◽

Vol 86 (4) ◽

pp. 669-675 ◽

Cited By ~ 10

Author(s):

Jiřı́ Petrák ◽

Daniel Vyoral

Keyword(s):

Labile Iron Pool ◽

Native Electrophoresis ◽

Blotting Technique ◽

Labile Iron ◽

Iron Pool

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Normoxic Stabilization of Hypoxia-Inducible Factor-1α by Modulation of the Labile Iron Pool in Differentiating U937 Macrophages: Effect of Natural Resistance–Associated Macrophage Protein 1

Cancer Research ◽

10.1158/0008-5472.can-05-2351 ◽

2006 ◽

Vol 66 (5) ◽

pp. 2600-2607 ◽

Cited By ~ 66

Author(s):

Helen J. Knowles ◽

David R. Mole ◽

Peter J. Ratcliffe ◽

Adrian L. Harris

Keyword(s):

Hypoxia Inducible Factor ◽

Natural Resistance ◽

Hypoxia Inducible Factor 1Α ◽

Labile Iron Pool ◽

Labile Iron ◽

Macrophage Protein ◽

Iron Pool

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Glutathione and the intracellular labile heme pool

BioMetals ◽

10.1007/s10534-020-00274-w ◽

2020 ◽

Author(s):

Rosemary O’Keeffe ◽

Gladys Oluyemisi Latunde-Dada ◽

Yu-Lin Chen ◽

Xiaole L. Kong ◽

Agostino Cilibrizzi ◽

...

Keyword(s):

Toxic Effects ◽

Intracellular Membrane ◽

Membrane Structures ◽

Aerobic Conditions ◽

Labile Iron Pool ◽

Heme Degradation ◽

Heme Transfer ◽

Labile Iron ◽

Iron Pool

AbstractOne candidate for the cytosolic labile iron pool is iron(II)glutathione. There is also a widely held opinion that an equivalent cytosolic labile heme pool exists and that this pool is important for the intracellular transfer of heme. Here we describe a study designed to characterise conjugates that form between heme and glutathione. In contrast to hydrated iron(II), heme reacts with glutathione, under aerobic conditions, to form the stable hematin–glutathione complex, which contains iron(III). Thus, glutathione is clearly not the cytosolic ligand for heme, indeed we demonstrate that the rate of heme degradation is enhanced in the presence of glutathione. We suggest that the concentration of heme in the cytosol is extremely low and that intracellular heme transfer occurs via intracellular membrane structures. Should any heme inadvertently escape into the cytosol, it would be rapidly conjugated to glutathione thereby protecting the cell from the toxic effects of heme.

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